CHEN, W-H., 2006. Disturbance observer based control for nonlinear systems. IEEE/ASME Transactions on Mechatronics, 9 (4), pp. 706-710 [10.1109/TMECH.2004.839034]
This paper presents a general framework for nonlinear
systems subject to disturbances using disturbance observer based control
(DOBC)techniques. A two-stage design procedure to improve disturbance
attenuation ability of current linear/nonlinear controllers is proposed
where the disturbance observer design is separated from the controller
design. To facilitate this concept, a nonlinear disturbance observer is
developed for disturbances generated by an exogenous system, and global
exponential stability is established under certain condition. Furthermore,
semiglobal stability condition of the composite controller consisting of a
nonlinear controller and the nonlinear disturbance observer is established.
The developed method is illustrated by the application to control of a
two-link robotic manipulator.